NAT(Network Address Translation)
The router technique that lets many private devices share one public IP address.
NAT is why inbound connections need port forwarding or a VPN to reach a device on your LAN. Understanding it is key to safe remote access.
Related articles
Port Forwarding
A router rule that directs incoming internet traffic on a specific port to a device on your local network.
Default Gateway
The device (usually your router) that traffic is sent to when leaving the local network.
CGNAT(Carrier-Grade NAT)
An ISP setup where many customers share one public IP, making inbound connections impossible without workarounds.